Skoda Fabia 1.9 tdi or Octavia 1.9 tdi will both tow your van the Fabia will return 40 towing and around 70 solo, these 1.9 tdi engines are good for 500,000 miles or more, as long as the oil is changed every 10,000
There are loads on auto trader look for a clean one with service history and before buying make sure the timing belt and water pump are changed

Well after much hunting I have bought a vectra petrol. Only 46k with full dealer history with a warranty for £3k. I know a diesel is better for towing but didn't want a high miler. The car is 140 HP so it should tow OK (I hope).